1,355,694 research outputs found
A spectral decomposition approach for the mechanical statistical characterization of distributed fiber-reinforced tissues
No full textWe discuss a spectral decomposition formulation for the mechanical statistical characterization of the anisotropic strain energy density of soft hyperelastic materials embedded with distributed fibers. We consider a generalized angular probability density function (PDF) of the reinforcement built upon the local eigenvalue and eigenvector system of the Cauchy–Green deformation tensor. We focus our analysis on material models dependent on the fourth pseudo-invariant of the deformation, I4, and on exponential forms of the fiber strain energy function. Within such a spectral reference system, we derive the closed-form expression of the PDF for I4 by generalizing the multi-value random variable transformation procedure recently developed in Gizzi et al. 2016. Our formulation bypasses the cumbersome extension–contraction switch, commonly adopted for shutting down the contribution of contracted fibers in models based on generalized structure tensors. Accordingly, we identify analytically the support of the fibers in pure extension for significant loading conditions. We can readily compute any statistics of the fourth pseudo-invariant and we can derive the direct definition of the average second Piola–Kirchhoff stress tensor according to the second order approximation
Due casi studio nell'Hinterland milanese: il Centro civico a Segrate e le Case IACP a Bollate di Guido Canella
No full textConservare l'oggi.
Relatori: Marco Dezzi Bardeschi, Philippe Daverio, Stefano Gizzi, Ugo Carughi, Gentucca Canella, Angelo Torricell
Cesare Brandi e la Sardegna. Archeologia e paesaggio
No full textScritti di Cesare Brandi relativi alla Sardegna, inquadrati nel più ampio panorama delle opere letterarie del Maestro, ma anche considerazioni sui restauri che nell'Isola si andavano compiendo, negli anni dei viaggi "sardi" del critico d'arte senese e, in generale, sulla tutela di un territorio ricco di valenze archeologiche, architettoniche e paesaggistiche, verificando quanto delle idee dello stesso Brandi sia stato recepito in quella straordinaria area geografica: tali sono gli spunti suggestivi che emergono dalla lettura di questo volume, che raccoglie gli Atti di una apposita giornata di studio tenutasi a Castelsardo nel settembre del 2007
Schede bibliografiche relative a tematiche sulle tecniche tradizionali per consolidamenti in zone sismiche
No full textSchede relative a sistemi tradizionali di consolidamento impiegati nel XVIII e XIX secolo in monumenti archeologici in area laziale.Records of traditional systems of structural reinforcement used in the eighteenth and nineteenth century in archaeological monuments in the area of Lazio
Ruth Rivera Marin and Her Commitment to Cultural Heritage
No full textIl documento, scritto insieme a Stefano Gizzi, affronta l'intensa attività di Ruth Rivera nel campo della protezione del patrimonio in Messico e America Latina alla metà del XX secolo. Dal 1952, Ruth Rivera è stata docente nell'ESIA di Teoria dell'Architettura, Composizione Architettonica, Pianificazione e Urbanistica e Teoria dell'Urbanismo. E tra il 1959 e il 1969 è stata a capo del Dipartimento di Architettura dell'Istituto Nazionale di Belle Arti (INBA). Ha partecipato attivamente nelle attività di diverse istituzioni nazionali e internazionali, tra cui l'Ordine degli Architetti del Messico, la Società di Architetti messicani, l'Associazione messicana di critici d'arte, ICOMOS, la Sottocommissione per i Musei dell'UNESCO; ed è stato presidente della International Union of Women Architects. Alcuni dei suoi principali scritti saranno esaminati e commentati, spaziando dalla pianificazione urbana alla protezione del patrimonio architettonico e artistico. Sarà anche considerato il suo ruolo nei lavori preparatori della Carta internazionale del Restauro del 1964 a Venezia, un documento ancora oggi essenziale per i principi teorici del restauro.The paper, written with Stefano Gizzi, affords the intense activity of Ruth Rivera in the field of heritage protection in Mexico and Latin America since the mid-twentieth century. From 1952, Ruth Rivera was a professor in the ESIA of Theory of Architecture, Architectural Composition, Planning and Urbanism and Theory of Urbanism. And between 1959 and 1969 she served as head of the Architecture Department of the National Institute of Fine Arts (INBA). She actively participated in various national and international institutions, among others, the College of Architects of Mexico, the Society of Mexican Architects, the Mexican Association of Art Critics, ICOMOS, the UNESCO Subcommittee of Museums; and served as president of the International Union of Women Architects. Some of her main writings will be examined and commented, ranging from urban planning to architectural and artistic heritage protection. It will also be considered her role in the preparatory work of the 1964 International Restoration Charter in Venice, a document still essential today for the theoretical principles of restoration
A microstructural model of crosslink interaction between collagen fibrils in the human cornea
No full textWe propose a simplified micromechanical model of the fibrous reinforcement of the corneal tissue. We restrict our consideration to the structural function of the collagen fibrils located in the stroma and disregard the other all-important components of the cornea. The reinforcing structure is modelled with two sets of parallel fibrils, connected by transversal bonds within the single fibril family (inter-crosslink) and across the two families (intra-cross-link). The particular design chosen for this ideal structure relies on the fact that its ability to sustain loads is dependent on the degree of the cross-link and, therefore, on the density and stiffness of the bonds. We analyse the mechanical response of the system according to the type of interlacing and on the stiffness of fibres and bonds. Results show that the weakening of transversal bonds is associated with a marked increase of the deformability of the system. In particular, the deterioration of transversal bonds due to mechanical, chemical or enzymatic reasons can justify the loss of stiffness of the stromal tissue resulting in localized thinning and bulging typically observed in keratoconus corneas
Pin-hole array production and detailed data analysis for advanced single-shot X-ray imaging of laboratory plasmas
No full textLaser produced plasmas offer the unique opportunity to investigate physical mechanisms working at extremely high field in pulsed regime [1] (Gizzi et al., 2009). Future large scale infrastructure like HiPER and ELI may open new frontiers of knowledge in this way. Technologies needed for improving diagnostic in this field have a strong impact on a wide range of multi-disciplinary applications as for compact plasma-based accelerators [1,2] (Gizzi et al., 2009; Betti et al., 2009) laser fusion oriented experiments, three-dimensional microscopy and lithography. As an example the X-ray imaging, being a powerful diagnostic tool for deep investigation on different variety of laser produced plasma, has obtained a grooving effort in recent years. Large scale facilities working in single-pulse regime for laser fusion oriented experiments have evidenced the necessity to obtain spectrally resolved X-ray images of produced plasmas in a single shot. By combining the charge coupled devices (CCD) based single-photon detection technique with a pin-hole array (PHA) a new diagnostic technique was developed, as shown in recent experiments related to the European HiPER project [3] (Labate et al., 2009). Here we qualitatively describe the PHA production process on a heavy metal substrate by means of SEM images that show an internal diameter on the micrometer scale and an aspect ratio of about 20. The characterization of the X-ray contrast up to 90 keV is presented. The data analysis of the X-ray photons interaction on CCD, for spectrum reconstruction up to high energy, is described [4] (Levato et al., 2008). (C) 2010 Elsevier B.V. All rights reserved. RI Gizzi, Leonida/F-4782-201
Exploring spring behaviour in the Aosta Valley (Italy): integrated harmonic and isotopic analyses for hydrogeological assessment
No full textMountain springs represent a vital component of the drinking water supply system in northern Italy, playing an essential role in meeting the needs of local communities. In recent decades, however, numerous hydrogeological challenges have emerged across the Italian Alps and Apennines, including diminished spring flow and the transformation of perennial springs into seasonal ones. Gaining insight into the recharge processes of these springs is critical for informed and sustainable water resource management.
Since 2010, the Applied Geology Research Group at the Politecnico di Torino has been conducting detailed monitoring activities in the Aosta Valley Region (northwestern Italy) (Gizzi et al., 2022). This work involves the use of multiparameter sensors in several springs—Promise, Entrebin, Gabiet, and Promiod—each situated in distinct mountain catchments. These sensors collect hourly data on water level, temperature, and electrical conductivity. Meteorological data, including precipitation and air temperature, are also gathered from nearby weather stations. To investigate recharge dynamics, hydrograph signals were analysed using Fast Fourier Transform (FFT), which enabled the decomposition of time-series data to identify correlations between discharge patterns, temperature changes, and precipitation events. Isotopic analyses (based on the V-SMOW2 standards) further contributed to the understanding of groundwater recharge origins, employing O-18 and H-2 isotopes to estimate the altitudes at which rain and snow infiltrate.
By combining these investigative approaches, the study has provided a more comprehensive view of spring recharge processes. Furthermore, the findings reveal how climatic fluctuations in mountainous regions influence spring discharge, offering valuable information for the development of sustainable management
strategies for alpine water resources.
Gizzi M. et al. (2022) - Aosta valley mountain springs: a preliminary analysis for understanding variations in water resource availability under climate change. Water, 14(7), 1004, https://doi.org/10.3390/w1407100
A generalized statistical approach for modeling fiber-reinforced materials
No full textWe present a generalized statistical approach for the description of fully three-dimensional fiber-reinforced materials, resulting from the composition of two independent probability distribution functions of two spherical angles. We discuss the consequences of the proposed formulation on the constitutive behavior of fibrous materials. Upon suitable assumptions, the generalized formulation recovers existing alternative models, based on averaged structure tensors both at first- and second-order approximations. We demonstrate that the generalized formulation embeds standard behaviors of fiber-reinforced materials such as planar isotropy and transverse isotropy, while any intermediate behavior is easily obtained through the calibration of two material parameters. We illustrate the performance of the model by means of uniaxial and biaxial tests. For uniaxial loading, we introduce a preliminary discussion concerning the generalized tension–compression switch procedure
Detailed characterization of the early x-ray emission of a plasma produced by point-like laser irradiation of solid Al targets
No full textA study of the dynamics of the x-ray emission from a point-like Al plasma produced by tight-focusing laser irradiation of a thick target is reported. Two-dimensional maps of the x-ray emission calculated at selected wavelengths show that, due to the rapid expansion cooling, x-ray emission mostly originates from a thin spatial layer. These properties enabled the results of the simulations to be compared with time-resolved x-ray spectra obtained under well-controlled experimental conditions. The outcome of this comparison is discussed in details, in view of the results reported in a recently published Letter [L. A. Gizzi, C. A. Cecchetti, M. Galimberti, A. Giulietti, D. Giulietti, L. Labate, S. Laville, and B. Tomassini, Phys. Plasmas 10, 4601 (2003)]. Moreover, the x-ray-reabsorption issues and the role of the Doppler decoupling mechanism in the presence of the strong velocity gradient typical of our experimental condition are discussed, also in view of a possible dedicated experiment. (c) 2005 American Institute of Physics
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